The task of a fire alarm system is that of detecting a fire as early as possible and triggering signals and notifications so that suitable measures can be initiated. It is thereby essential for the fire alarm system to function reliably in order to ensure that appropriate signaling can occur in timely manner in the event of fire.
It is frequently the case that a fire alarm system is not only designed to signal a fire hazard but also to detect same and even undertake suitable measures as applicable. A fire alarm system inasmuch usually consists of a number of interlinked components such as automatic fire alarms, manual fire alarms, acoustic or optical signaling devices or extinguishing system components. These components are connected to a central fire alarm control panel via one or more transmission path(s).
To that end, using a ring bus system to link the components of a fire alarm system to a central fire alarm control panel and/or control unit is known in the field of fire prevention. The advantage of a ring bus system can be seen in all the connected bus nodes continuing to remain responsive to the control unit even in the event of a short or open circuit.
Reference is made in this context to printed publication EP 1 363 261 A1 which discloses a ring bus system of a hazard alarm system.
However, the ring bus systems known from the prior art in the fire prevention field exhibit disadvantages in practical use resulting from the limited bandwidth of the bus systems. The limited bandwidth leads to typical query times of all the components connected to the ring bus system, such as for e.g. status polling (alarm/malfunction status), amounting to several seconds. Typical restart times for the ring bus system after a line failure are in the range of one to five minutes.
Although these response times are entirely sufficient for operation of a fire alarm system according to the EN 54-13 standard (August 2005), the response times are not suitable for detecting analog values of sensors connected to the bus system, for example gas sensors of an oxygen-reducing system, at sufficient resolution or sampling. Nor do the response times of the known prior art ring bus systems meet the time-based requirements of an electrical control and delay device (ECD) for fire extinguishing systems as per e.g. EN 12094-1 or VdS 2496.